1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel, apparatus for fabricating the same, and fabrication process thereof.
2. Background of the Related Art
This is the age of multimedia, which requires a display enabling to give expression to colors almost the same of the nature as well as fine and large image. For a wide display over 40 inches, it is difficult to introduce the, present CRT(cathode ray tube) and LCD(liquid crystal display) structures. Instead, a plasma display panel attracts public attention in a field of a next generation display.
Such a plasma display panel, as shown in FIG. 1A, is constructed with upper and lower plates 10 and 20 confronting and combined each other. FIG. 1B shows a cross-sectional structure of the plasma display panel in FIG. 1A, in which a face of the lower plate 20 is rotated by 90xe2x96xa1 for the convenience of explanation.
The upper plate 10 is constructed with scan electrodes 16 and 16xe2x80x2 and sustain electrodes 17 and 17xe2x80x2 which are parallel each other, a dielectric layer 11 formed on the upper plate 10 including the scan electrodes 16 and 16xe2x80x2 and sustain electrodes 17 and 17xe2x80x2, and a passivation layer 12 on the dielectric layer 11. And, the lower plate 20 is constructed with address electrodes 22, a dielectric body layer 21 formed on an a front face of the plate including the address electrodes 22, partition walls 23 formed on the dielectric body layer 21 between the address electrodes 22, and a fluorescence material 24 formed on surfaces of the partition walls and dielectric body layers 21 in the respective discharge cells. And, mixed inert gas such as He, Xe and the like fills up a space between the upper and lower plates 10 and 20 so as to form a discharge area.
Operation of the above-constructed plasma display panel follows.
First, when a driving voltage is applied thereto, a confronting discharge occurs between the address and scan electrodes, whereby portions of electrons discharged from the inert gas in the discharge cells collide with a surface of the passivation layer. Subsequently, secondary electrons are discharged from the surface of the passivation layer by the collision of the electrons. Then, the discharged secondary electrons collide with plasma gas so as to spread the discharge. After the confronting discharge between the address and scan electrodes finishes, wall charges having opposite polarities are generated from the surface of the passivation layer on the address and scan electrodes.
When the driving voltage being applied to the address electrodes is cut off while the discharge voltage having opposite polarities is continuously applied to the scan and sustain electrodes, plane discharge occurs in the discharge area of the surfaces of the dielectric layer and passivation layer by a potential difference between the scan and sustain electrodes. Such confronting and plane discharges make the electrons in the discharge cell collide with the inert gas in the discharge cell. As a result of this, the inert gas in the discharge cell becomes excited and produces an ultraviolet ray having a wave of 147 nm in the discharge cell. Such an ultraviolet ray collides with the fluorescence material surrounding the address electrode, thereby realizing an image.
In order to make the plasma display panel exhibit its performance and elongate its durability, the layers inside the panel should be built solid and no impurity gas except the discharge gas should exist.
A process of fabricating such a plasma display panel may be divided into three parts such as a former process, a latter process, and a module process.
First, the former process is a process of forming various layers on the upper and lower plates 10 and 20. The latter process includes combination of the upper and lower plates 10 and 20, exhaust, discharge gas injection and tip-off, aging, and inspection. In this case, the tip-off is a process comprising the steps of completing the exhaust and discharge gas injection through an exhaust pipe and cutting and sealing the exhaust pipe. And, the aging is a process for removing impurities finally by driving electrodes for a predetermined time by applying a voltage thereto so as to attain a discharge voltage drop.
Finally, the module process is the last process of mounting circuits and assembling parts so as to complete a plasma display panel.
An apparatus for fabricating a plasma display panel and a method of fabricating a plasma display panel according to a related are explained as follows by referring to the attached drawings.
FIG. 2 illustrates a latter process for a plasma display panel and a process condition thereof according to a related art, FIGS. 3A to FIGS. 3C illustrate layouts for explaining a combining process in FIG. 2, FIG. 4 illustrates a cross-sectional view of an exhaust pipe, FIG. 5 illustrates a layout of a combination/exhaust separate type apparatus for a display panel according to a related art, and FIG. 6 illustrates a cart structure in FIG. 5.
The latter process for a plasma display panel(hereinafter abbreviated PDP) according to related art, as shown in FIG. 2, includes combination of the upper and lower plates 10 and 20, exhaust, discharge gas injection and tip-off, aging, and inspection.
First, the upper and lower plates 10 and 20 are transferred to a combination apparatus. And, an edge of the upper plate 10, as shown in FIG. 3A, is coated with a sealing material 31, i.e. frit, to the uniform thickness using a dispenser. In this case, the frit consists of glass, SiO2, and an additive for improving adhesiveness.
And, they are dried at about 120xc2x0 and thermally treated at a high temperature over 400xc2x0 C. in order to remove impurities remaining in the frit.
Then, the thermally-treated upper and lower plates are transferred to a combination apparatus. In this case, the upper plate 10 is transferred to the combination apparatus by being exposed to the atmosphere.
AS shown in FIG. 3B, the upper and lower plates 10 and 20 are aligned to each other in the combination apparatus. And, the upper and lower plates 10 and 20 are fixed by combination clamps 32. Then, the upper and lower plates 10 and 20, as shown in FIG. 3C, are combined with each other by melting the frit.
When carrying out the combination process, an exhaust pipe 40 consisting of a long-straw type glass is attached to an exhaust hole 42 of the lower plate 20 using a frit ring.
Then, a panel of which combination is finished is transferred to an exhaust and gas injection apparatus.
The exhaust and gas injection apparatus carries out an exhaust process exhausting impurities sticking to a layer and impurity gas generated from the layer outside using the exhaust pipe 40 formed in the combination process.
Then, discharge gas is injected through the exhaust pipe 40. And, a tip of the exhaust pipe 40 is tipped off by applying a heat thereto, thereby preventing the leakage of the injected discharge gas.
Subsequently, the process is completed by inspecting a state of the panel after the aging.
Thus, a separate type fabrication apparatus, which carries out the combination and the exhaust and gas injection separately in exhaust pipe type fabrication apparatuses, is divided into the combination apparatus and the exhaust and gas injection apparatus. The exhaust and gas injection apparatus, as shown in FIG. 5, includes a hot-wind heating furnace 51 to establish an exhaust and discharge gas injection condition and a cart 52 loading a panel and unloading the panel on which the exhaust and discharge gas injection has been carried out in the hot-wind heating furnace 51.
The cart 52, as shown in FIG. 6, is constructed complicatedly with a vacuum pump 61 to make vacuum inside the panel, a vacuum pipe system including an exhaust manifold 62, valves and pipes, a bombe 65 for discharge gas injection, a gas injection pipe system including a gas injection manifold 63, valves and pipes, and a tip-off unit 64 to tip off the exhaust pipe 40.
Unfortunately, the above-constructed pipe type PDP fabrication apparatus and fabrication process thereof contains the following problems.
First, impurity gas in a gap between the upper and low plates, which are combined with each other and leave an interval of several microns, of the panel over 40 inches wide has to be sucked through a long and narrow exhaust pipe, which takes at least several hours in a high vacuum state of 10xe2x88x927 Torr. Thus, the bottleneck of a product process is resulted. Therefore, the number of apparatuses increases for mass production, thereby failing to avoid increasing a space for the apparatuses.
Second, an intense heat is applied thereto in a high vacuum state, which carries a massive load on the panel. And, the panel is formed of glass vulnerable to heat deviation and pulling intensity, thereby failing to avoid panel damage or panel characteristic degradation.
Third, the exhaust pipe also made of glass may be broken by an impact on transference or temperature variance on exhaust, whereby automation of the panel fabrication is hardly achieved.
Fourth, the plastic process is carried out to remove the impurities of the frit. Yet, energy loss is increased due to heating and cooling of the plastic process. And, a great deal of impurities is generated again from the frit due to the high heat applied thereto during the combination process. Thus, the exhaust time is increased and the frit fragile to external impact may cause the panel breakage due to the external impact.
Fifth, the passivation layer of the upper plate is formed to play an important role for the prevention of the damage on the electrodes during discharge. But, the passivation layer exposed to the atmosphere is transferred to the combination process and then the exhaust and discharge gas injection process is carried out. xe2x80x98MgOxe2x80x99 widely used as a material for the passivation layer is easy to be contaminated by being combined with the atmospheric components such as H2O and the like. Therefore, degradation of product performance and reduction of product durability are brought about.
Sixth, an intense heat is applied thereto in the high vacuum state on combining the upper and lower plates so as to carry a massive load on the panel formed of glass vulnerable to heat deviation and pulling intensity, thereby failing to avoid panel damage or panel characteristic degradation.
Seventh, the plastic process is carried out to remove the impurities of the frit. Yet, energy loss is increased due to heating and cooling of the plastic process. And, a great deal of impurities is generated again from the frit due to the high heat applied thereto during the combination process. Thus, the exhaust time is increased and the frit fragile to external impact may cause the panel breakage due to the external impact.
Besides, in order to overcome the above problems, proposed are a tip-less process using no exhaust pipe and a semi-tip-less process injecting discharge gas through an additional hole instead of filling in the chamber with discharge gas. However, theses processes fail to prevent the generation of impurity gas penetrating into the panel, thereby causing the discharge gas contamination which is the fatal defect of the no-pipe process. Thus, both of the tip-less and semi-tip-less fail to be applied to the product production practically.
Accordingly, the present invention is directed to a plasma display panel, apparatus for fabricating the same, and fabrication process thereof that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a plasma display panel, apparatus for fabricating the same, and fabrication process thereof enables to reduce the time for a product process and prevent panel characteristic reduction and panel damage by preventing the generation of impurity gas and achieving the plates-combination at a room temperature.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, an apparatus for fabricating a plasma display panel according to the present invention includes a passivation layer formation means for forming a MgO passivation layer on a first substrate, a substrate transfer means for receiving the first substrate from the passivation layer formation means, the substrate transfer means transferring the received first substrate and a second substrate inserted therein to a next fabrication stage, a cleaning means for removing impurities existing on the first or second substrate transferred through the substrate transfer means, a sealing material coating means for coating a sealing material on the first substrate transferred through the cleaning means, and a discharge gas injection/combination means for injecting discharge gas inside, the discharge gas injection/combination means for aligning precisely the first substrate transferred through the sealing material coating means and the second substrate with each other using an alignment robot, the discharge gas injection/combination means for combining the first and second substrates with each other.
In another aspect of the present invention, a process for fabricating a plasma display panel using an ultraviolet ray producing means according to the present invention includes the steps of coating a predetermined area of a first substrate with a sealing material having elasticity and hardened by ultraviolet rays, aligning a second substrate with the first substrate, and combining/attaching the first and second substrates with/to each other by applying the ultraviolet rays to the sealing material with the ultraviolet ray producing means.
In a further aspect of the present invention, a plasma display panel includes a first substrate, a sealing material coated on a predetermined area of an effective image circumference of the first substrate, the sealing material having predetermined width and height, a second substrate aligned over the first substrate, the second substrate adhering closely to a surface of the sealing material, and a plurality of pressurization means for applying a predetermined pressure so as to maintain a combination/attachment state between the first and second substrates, the pressurization means mounted along the circumference of the first substrate and a circumference of the second substrate with a predetermined interval therebetween.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.